Method for preparing 1, 1-dicyano ethyl substituted 1, 3-diketones



United States Patent C) METHOD FOR PREPARING 1,1-DICYANO ETHYLSUBSTITUTED 1,3-D1KETONES Jerome C. Westfahl, Cuyahoga Falls, Ohio,assignor to The B. F. Goodrich Company, New York, N. Y., a corporationof New York No Drawing. Continuation of application Serial No. 523,124,July 19, 1955. This application April 15, 1957, Serial No. 652,655

17 Claims. (Cl. 260-464) This invention relates to a method offormingderivatives of dicarbonyl compounds having 1,1-dicyano ethylgroups as substituents and more particularly pertains to a method ofpreparing 1,3-dicarbonyl compounds having at least one 1,1-dicyano ethylgroup replacing an active hydrogen atom of the methylene group byreaction of the 1,3-diketone with monomeric 1,1-dicyano ethylene in theabsence of a catalyst.

It is known that compounds with an active methylene group can bereacted, in the presence of strong basic catalysts, to form derivativesin which one or both hydrogen atoms of the methylene group are replacedwith an aliphatic substituent. Classical examples of such a reaction arethe so-called Michael condensation inwhich a compound containing anactive methylene group is reacted with acrylonitrile in the presence ofa strongly alkaline catalyst to form a cyano ethyl substituted methylenederivative. In the absence of a catalyst the reaction either does notproceed or the yields are of a-very low order even if the reactants areallowed to remain in contact with each other over extended periods oftime.

A base-catalyzed reaction between monomeric 1,1- dicyano ethylene andactive methylene compoundsis not possible, because the 1,1-dicyanoethylene polymen'zes very rapidly under such reaction conditions,even'in the presence of an inert diluent, such as a liquid hydrocarbon.Monomeric 1,1-dicyano ethylene is so reactive that the presence ofalmost any ion, water, alcohol or amine will cause polymerization of themonomer.

An object of the invention is the provision of a method for preparing1,1-dicyano ethyl substituted 1,3-dicarbonyl compounds by reacting thelatter with monomeric 1,1-

dicyano ethylene in the absence of a catalyst.

Another object is the provision of a method .of reacting monomeric1,1-dicyano ethylene with 1,3-dicarbonyl compounds in the absence of acatalyst at elevatedtemperatures to form substituted derivatives.

Numerous other objects will be apparent from the following detaileddisclosure which describes the preferred embodiment of the invention.

The above objects are accomplished by reacting monomeric,homopolymer-free, 1,1-dicyano ethylene with a 1,3-dicarbonyl compoundhaving the generic structure R(ILLCH2(UJR in which R represents analkyl, aryl, aralkyl or alkaryl saturated hydrocarbon or halogenatedderivatives thereof "Ice 2,864,850 Patented Dec. 16, 1958 II0.10H21-C-0Hpi1-CH3 to CmHu v 0 i ll CiaHaPiJ-CHHC-QH: to CHEM o 0 II II-mm-o-cm-o-on; to CnHsI E-CHr-E- ii if CzHr-O-OHrC-CaH 0 II ICnHn-C-CHr--O CH: to 01:13::

0 ll ll om-o-om-c-om-O ll ll CHr-C-CHa-C-OCHs t0 CuzHsr O O H II (CnHh)y CHr-C-CHr-C-O OH; to Clans? In the above formulas n represents aninteger from I to 6 and y represents an integer from 1 to 3.

In addition to the 1,3-dicarbonyl compounds specified above, thehalogenated derivatives will also react to form 1,1-dicyano ethylsubstituted derivatives.

The reaction will proceed slowly at room temperature, but it ispreferred to use an elevated temperature of about 120 C. or higher,since the reaction rate at the elevated temperatures is markedly greaterthan that at lower temperatures.

The reaction between 1,3-dicarbonyl compounds and 1,1 -dicyano ethylenecan be carried out either in the presence or absence of an inertdiluent. If the 1,3- dicarbonyl compound is liquid at room temperatureor slightly above, I prefer not to use any diluent or Solvent, but with1,3-dicarbonyl compounds which are solid at room temperature it ispreferable to employ an inert diluent in which both the 1,1-dicyanoethylene and the 1,3-dicarbonyl compounds are soluble. Solvents for thereaction system include the saturated halogenated aliphatic hydrocarbonssuch as chloroform, carbon tetrachloride, tetrachloroethylene etc., orthe liquid aromatic hydrocarbons such as benzene, toluene, xylene etc.Monomeric l,l-dicyano ethylene will react with a wide variety ofmono-unsaturated compounds to form copolymers and with conjugated dienesto form Diels-Alder type adducts; and for these reasons when a diluentis used it is essential that it be non-reactive.

A further essential condition is that the 1,1-dicyano ethylene is freeof any homopolymer of the 1,1-dicyano ethylene, because even smallamounts of the homopolymer appear to catalyze further polymerization ofthe 1,1- dicyano ethylene and thereby make the 1,l-dicyano ethyleneunavailable for reaction. If desired, polymerization inhibitors such asP 0 can be optionally added to the reaction mixture without interferingwith the main reaction course.

The following examples are intended to be illustrative of the inventionand are not intended to be construed as limitations thereon. In allinstances parts are expressed by weight unless otherwise specified.

Example 1 Ethyl acetoacetate was added to a three necked flask to whicha reflux condenser, a stirrer and a separatory fun nel were connected.The ethyl acetoacetate was heated to IOU- C. and a solution of freshlydistilled monomeric 1,1-dicyano ethylene in ethyl acetoacetate wasslowly added to the flask. The reaction temperature of 100 C.110 C. wasmaintained until the characteristic odor of monomeric 1,1-dicyanoethylene was absent 5 The ratio" or the total ethyl ace'to'ac'etate to1:,1-dicyano ethylene was. about 4 to 1. The reaction product gen andnitrogen with the following results.

Calculated for OmHnOaNQ Fmmd 57K 28 61 77 131 27 The 2(1,1-dicyanoethyl) ethyl acetoacetate was hydrolyzed by refluxing with aqueous HClfor 5 hours. Gamma-acetylbutyric acid was isolated in a 77.4% yield fromthe hydrolysis mixture. The gamma-acetylbutyric .acid was converted toits semi-carbazone which had a .M. P. of 173 C., with decomposition, andto its oxime which hada M. P. of '3.5-"l'04.5 C. These compounds compare"favorably with the reported values of 173- '174" C. and 104-105 C. forthe scmi-car'bazone and oxime, respectively.

Example II The general procedure described under Example I was followedwith the exception that acetylacetone was used in place of the ethylacetoacetate. A yield of 63.7% of a solid having a 'meltingpoin't-of101--104.-5 C. was recovered.

0n analysis the following --p'ercentages were found:

Galculated for C9H1002N2 60.66 5.66 15.72 Found 60.58; 5.71 15.72

The solid t i t CH3C-'C|l-C-CH ornoruolvu was-hydrolyzed by refluxing inaqueous HCl for 3 hours. Extractionof the hydrolysis mixture gave a 68%yield, based on the 1,1-dicyano ethylene, of impure gammaacetylbutyricacid which had an odor of acetic acid. A semi-carbazone of the impureketo acid had a M. P. of 173.5 C. and the melting point of a mixture ofthis semicarbazone with an authentic semi-carbazone ofgammaacetylbutyric acid was not depressed.

Example III To a solution-of dibenzoyl methane in dry chloroform wasadded a chloroform solution of freshly distilled 1,1- dicyano ethylene.The molar ratio of dibenzoyl methane to 1,1-dicyano ethylene was 1 to 2.The reaction was maintained at reflux until the odor of monomeric 1,1-dicyano ethylene was no longer detectable. A solid, recovered from thereaction, was found to be a mixture of CHaC (C )2 and The monoand thebis-substituted dibenzoyl methanes can 'be separated by theirdifierences in solubility in several organic solvents. By way-of examplethe mono-substituted dibenzoyl methane is readily soluble in benzenewhile the bis-substituted derivative is practically insoluble. The M. P.of the mono-substituted derivative was: 114.5- 115.5" C. and" thatof thedisubstituted compound was 1'7 5 .5--177 C. with decomposition. Thevformation of the bis-substituted derivative could not be prevented byusingaan excess of dibenzoyl methane in the reaction mixture.

Hydrolysis of -1(C H' CO) CHCH CH(CN) by refluxingin aqueous 'HCl for1-6 hours yielded a mixture of acids which. were separated by steamdistilling, which proved -to be benzoic acid, and then recovering anonvolatile acid which was found to be gamma-benzoylbutyrric acid. Thelatter melted at 128.5129.'5 C. It was converted to its semi-carbazonewhich melted at 210-! 21.0.5 C. with decomposition. 7

Acid hydrolysis of the cyclic disubstituted compound yielded benzoicacid and an. acid which was only slightly soluble in-chloroform. 1tha'dan M. P. of 1375-138 C. Onan'alysis the following results wereobtained:

Calculated at 01.111505 Found 63368 The neutral'equiva'lent was 131. Onthe basis of these data the structure of To a solution of benzoylacetone in dry chloroform containing solid P 0 was added a solution offreshly distilled monomeric 1,1-dicyano ethylene in the same solvent.The molar proportions of each reactant was I to 1. The mixture washeated at reflux .temperature until the odor of 1,1-dicyano ethylene wasonly slightly discernible. Colorless crystals in a yield of 45.8%, andhaving a melting p'oint'of 9'6.7-197.7 C. were recovered by distillationof the liquid diluent and recrystallization of the solid residue fromalcohol containing activated carbon. Analysis showed that it contained69.80% C, 4.95% H and 11.71% N as compared to calculated values of69.98%, 5.04% and 11.66% respectively for the mono-1,1-dicyano ethylsubstituted benzoyl acetone.

Example V Ethyl benzoyl acetate was added to a reaction flask and heatedto 110 C. Monomeric 1,1-dicyano ethylene was added slowly over about 20minutes to the ethyl benzoyl'acetate, in such quantity that the molarratio of the ethyl benzoyl acetate was twice that of themonomeric1,1-dicyano ethylene. Heating'was continued "for about two hours.Thereafter the excess ethyl benzoyl acetate was removed by distillationunder reduced pressure. A

was analyzed and gave the following results:

Calculated f0! CuHuOgN 66. 65 5. 22 10. 37 Found 66. 50 5. 12 10. 30

On hydrolysis gamma-benzoylbutyric acid having a M. P. of l28.5-l29.5 C.was recovered. This hydrolysis product was further identified byconversion to its semicarbazone.

In my copending application Serial No. 523,121, filed July 19, 1955, nowPatent 2,804,469, I describe and claim methods of preparing other monoand his 1,1-dicyano substituted active methylene compounds by reactingin the presence of an alkaline catalyst, a homopolymer of 1,1-dicyanoethylene with an active methylene compound having an ionization constantin water at 25 C. of at least 1X10- together with the products whichresult from the reaction.

Although I have described this invention by reference to specificexamples, they are intended for illustrative purposes only. Accordingly,this invention is intended to include all the variations andmodifications falling within the spirit and scope of the claims. Thisapplication is a continuation of my patent application Serial No.523,124, filed July 19, 1955, now abandoned.

I claim:

1. A method of preparing compounds having at least one CH CH(CN)substituent in place of at least one hydrogen atom of a methylene groupattached to two carbonyl carbon atoms comprising reacting a compoundhaving a linkage as the sole functional linkage with monomeric1,l-dicyano ethylene containing substantially no homopolymer thereof, inthe absence of a catalyst.

2. A method of preparing compounds having the structure wherein R and Rhave the same designation as above.

3. The method of claim 2 in which the reaction is carried out at anelevated temperature.

4. The methodof claim 2 in which the 1,3-dicarbonyl compound is a1,3-diketone.

5. The method of claim 2 in which the 1,3-dicarbonyl compound is abeta-keto carboxylic acid ester.

6. A method of preparing it i if CHaC-C|$-CCH2 comprising reactingacetylacetone with monomeric 1,1- dicyano ethylene in the absence of acatalyst.

7. A method of preparing a mixture of CHaCH(CN)z and comprising reactingdibenzoyl methane with monomeric 1.1-dicyano ethylene in the absence ofa catalyst.

8. A method of preparing comprising reacting ethyl acetoacetate withmonomeric 1,1-dicyano ethylene in the absence of a catalyst.

11. A method of preparing comprising reacting ethyl benzoylacetate withmonomeric 1.1-dicyano ethylene in the absence of a catalyst.

12. Compounds having the structure in which Y is hydrogen and when R andR each is an aryl group Y also represents a 1,1-dicyano ethyl radical, Zrepresents a 1,1-dicyano ethyl radical, R is selected from the classconsisting of alkyl group having from 1 to 18 carbon atoms, a phenylgroup and a phenyl substituted lower alkyl group and R is selected fromthe class consisting of alkoxy and alkyl groups having from CHr-LZv-ZLCH,

CHr-CH(CN)! References Cited in the file of this patent UNITED STATESPATENTS 2,804,469 Westfahl Aug. 27, 1957 UNITED STATES PATENT OFFICECertificate of Correction Patent No. 2,864,850 December 16, 1958 JeromeC. Westfahl It is hereby certified that errorappears in the printedspecification of the above numbered patent requiring correction and thatthe said Letters'Patent should read as corrected below.

Column 4, lines 1 to 6, the formula should appear as shown below insteadof as in the patent:

o 0 II E C-CHr- OCH; to 01111 column 8, lines 58 to 63, the formulashould appear as shown below instead of as in the patent Signed andsealed this 5th day of May 1959.

[SEAL] Attesi'fi KARL H. AXLINE, Attesting Ofiicer.

ROBERT C. WATSON,

Commissioner of Patents.

1. A METHOD OF PREPARING COMPOUNDS HAVING AT LEAST ONE -CH2-CH(CN)2SUBSTITUENT IN PLACE OF AT LEAST ONE HYDROGEN ATOM OF A METHYLENE GROUPATTACHED TO TWO CARBONYL CARBON ATOMS COMPRISING REACTING A COMPOUNDHAVING A